Dry cell



May 15, 1928. 1,670,040

E. H. M ABE DRY CELL Filed Dec. 22, 1924 Patented May 15, 1928.

UNITED STATES PATENT. OFFICE.

g EUGENE E. IcCABE, OF MADISON, WISCONSIN, ASSIGNOB TO FRENCH BATTERY COK- PM, 01 MADISON, WISCONSIN, A CORPORATION OF WISCONSIN.

DRY CELL.

Application fled liecember 22, 1924. Serial No. 757,403;

The present invention is in the nature of animprovement in dry cells; and the pnmary object is to provide a dry cell, especially the type employed for use in flash-- 5 lights, in which themetallic cap ordinarily employed on the. carbon electrode is omitted, and a metallic end-facing for the carbon is supplied in accordance with the method herein described.

The invention is illustrated in the accompanying drawing, in which- Fi ure 1 represents a sectional view of a flash ight containing two cells constructed in accordance with the invention; Fig. 2, a sectional view of one of the cells shown in Fig.

1;'Fig. 3, a broken sectional view of the uprend portion of the carbon electrode; and

ig. 4, a view illustrating the manner in which carbons may be suitably tipped with metallic coatings, in accordance with the present method. v

7 Referring to Figs. 1 and 2, A represents a flashlight casing equipped closing device A, and B, dry cells adapted for use in said flashlight.

In the construction illustrated, each dry" cell comprises a zinc container, 1, having its upper end closed by a suitable sealing compound 2; a compacted core 3 of depolarizing mixture usually comprising manganese dioxid and carbonaceous material; a carbon electrode 4 embedded in the core 3, and having its upper end extending through the seal 2; electrolyte 5 filling the space. between I 3 the core and thecontainer; and apasteboard washer 6 disposed beneath the sealing compound and separated from thecore and electrolyte by an air space 7.

In accordance with the present method,

- 40 the upper end surface. of the carbon electrode is coated with a metallic powder, as indi'-. cated at 4; and, if desired, this coating may be reflected over the upper circumferential portion of the carbon, as indicated at 4*. The metallic powder should be so applied as to force particles thereof into the pores-of the carbon and build up a-Inetallic surface,

which may, however, constitute only a thin film above the surface of the carbon. Ac-

cordingly, the metallic powder is sprayed, or forced, against the surface of the carbon at short range and under comparatively highpressure. Iressure employed for the purpose may be pneumatic pressure.

i It is preferred t9 use a coating composed with a circuit-- which an air blast is supplied for carrying the particles of metal, as they are freed from the wire against the surface of the carbon. Such device will operate somewhat as a blowtoreh, and will effect the melting and .disintegration of the end ortion of the wire fend Will carry the partic es of metal, with great force, against the carbon. By this method, the particles of metal are forced into the ores of the carbon, and a metal film is built upon the end surface of the car bon and firmly anchored in the carbon.

Suitable pressure for the sprayin of oxygen and h drogen to the frame is' a out thirty p'oun s per square inch; and suitable pressure for the compressed air employed for blowing the metal particles against the carbon is about one hundred pounds per square inch. A lower pressure will suffice, however. The end of the nozzle may be placed a few inches from the carbon to be coated.

As has been indicated, the particles of metal are' first driven into the pores of the ,carbon, and finally the entire surface of the carbon becomes coated. Sufiicient fusing of the particles occurs, apparently, because of the heat of collision, to cause the particles to coalesce, or become united, and form a film which completely covers the end surface of the carbon. The metallic surface thus .produced on the carbon is a fine, granular surface,'and afi'ords an excellent electrical contact.

While in the illustration given, the coating is shown as carried down over the circumferential surface of the carbon for a short distance, in practlce this is unneces vsary. In fact, if desired, the-metallic surface. or; film, may be applied only to a restricted area on the central portion of the end surface of the carbon. In other Words,

it need notextend outwardly from the central point wholly .to the circumference of the end surface. A certain advantage can be obtained by thus restricting the coated area, inasmuch. as by' this method, a suflicicnt area of contact for the purpose of the I electric circuit can be obtained Without cov eriug the Whole end surface of the carbon. "Where the restricted area of coating is employed, there is less liability that corroslon of the metal will occur in the use of the cell.

Where, for example, a brass cap is emplo ed on the carbon, there is danger that some e eczinc can. Thus, not only is the efiiciency "of the cell lowered and its life shortened, but

the contact is injured, or rendered less con-' ductive, so that the best results are not ob tained with flash-lights employing such construction. Where, in accordance with the present invention the area of metallic contact is limited wholly to the end surface of the carbon, or is confined to the central portion of the end surface of the carbon so as to presentonly a film like disk of small, diameter, there is less likelihood of the electrolyte reaching the metal and causing the injury from corrosion which has been mentioned.

v I Referring to Figl l, Q represents shieldwhich may be of metal, cardboard, .or any suitable materialf This shield :is provided.

with perforations 8 which receive, or to which are presented, the ends of the carbons 4. The shield may be pf any desired'size and may accommpdate as man carbons as desired. It may serve as a ho der for the emoeo carbons, or any suitable holder may be provided. By thejuse of such a device, the end surfaces of a. batch of carbons may-be pre-- sented to the torch, or gun, and the spraying of the end surfaces may be quickly and cheaply effected.

Any other suitable method of driving fine particles of metal, at high speed,against the end surface of the carbon may be employed, the object being, first, to embed particles in .theporcs of the carbon, and then cause coalescence of the particles as the spraying operation proceeds, so that a fine, granular v film on the end surface of the carbon resu ts which is well anchored to the carbon. e

film may be burnished, or polished, if dc sired, but ordinarily, this will be unnecessary. Any suit-able metal may be employed instead of copper or brass. The metals most resistantto corrosion, such as copper, brass, zinc, etc., are preferred, however.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claim should be construed as broadly as permissible, in view of the prior art.

What I regard as new, and desire to secure by Letters latent," is: r

The method of applying a metal filmto theend-portion-of a' carbon pole which com-' prises melting the point of a metal wire and a forcing the particles of metal as they are freed from the wire against the surface of the carbon bymeans of an air-blast which serves to embed the metal particles in the pores of the carbon and then' build upa metal film thereon.

EUGENE H. iremen 

